The advantages of irreversible drugs in both the in vivo and in vitro evaluation of opiate action has led to the recent development of a number of irreversible opiate agonists and antagonists (Caruso et al. Science 204: 316-318, 1979; Portoghese et al, J. Med. Chem. 22: 168-173, 1978; Portoghese et al, J. Med. Chem 22: 168-173, 1979; Schultz and Goldstein, Life Sc. 16: 1843-1848, 1975; Winter and Goldstein, Mol ec Pharmacol 8: 601-611, 1972). One compound, naloxazone, has been particularly useful in characterizing opiate receptors and opiate actions because of its ability to selectively inhibit the high affinity, or mu.sub.1, binding sites as well as blocking opiate analgesia with little effect on other classes of binding sites or opiate-induced lethality (Pasternak et al Science 208: 514-516, 1980; J. Pharmacol Exp. Therap 214: 455-462, 1980; Zhang and Pasternak, Life Sc. 29: 843-851, 1981; Pasternak; in press). However, naloxazone requires high doses both in vivo and in vitro to inactivate these high affinity, or mu.sub.1, binding sites and the mechanism of its activity was unrecognized (mu site classification is described in-Wolozin and Pasternak, Proc. Natl. Acad. Sci., Vol. 78, pg, 6181-6185 (1981).